Sewing machine



Oct. 1l, 1938. B. w. DAVIDSON SEWING MACHINE Filed Sept. 9, 1937 2 sheets-sheet 2 13.4. Boo/4er .pav/S07? gamen,

Patented Oct. 11, 1938 n #SEWING ivmoHINr: p

Booker WlDavidson, Michigan .City,'Ind.r f l applicatioe'september' 9, 1931-, seala No. 163,129] aclantis.v (c1. 1ra-201),l p

My invention relates to improvementsin sewing machines of the so-called chainestitch type.

The primary object ofmy invention is to equip a double thread machine for thieformation of a reinforced chain stitch, and with improved loop forming and manipulating*mechanism.'y

Another object is to provide arrimpioved'thread supply -for suchr machines together with efficient guiding and thread.

Other and subordinate objects fare*V valso comj-j' prehended by my invention, all' of which` together with the exact nature of 'my improvements, will be readily understood when the following descrip? tion and claims are read withrreferenfce l'to the accompanying'drawings. v

In said drawings: Figure 1 is a View partly in sideelevation and partly in sectionof a my improvements. Y

Figure 2 is a view inA perspective of :my improved guiding and tensioning means for the lower thread and a rotary 'hookor' `lfooptaker associatedtherewith. l v Figure 3 is a View in Vperspective of thethread guiding andtensioning means and loop taker illustrating operation of thelatter.

Figure 4 is a perspective View of a loopfpick up mechanism.

Figure 5 is a perspective view' illustrating the formation of the stitch, and" Figure 6 is a side elevation of a threading hook.

Referring to the illustrated embodiment ofmy. invention in" detail, with reference thereto by numerals," designates the usual bed plate of the Singer sewing machine of commerce, V2 thestand V ard thereof; 3 the tubular arm, 4 thehead, and 5 the balance wheel. Associated withthe head 5.

is the usualV thread takeup Vlever 6; tensioning disks 'Ifor the upper thread, thread guides and of the drive shaft'l3, thev jack shaftk |31 the bevel' gear drive I4 between said shafts" andthe beviel' gear |4' on the jack'shaftl3f alici-which form part vof therusual driveffor the.'rotary"h .)ok.orV

loop taker of 'theI well knoWnjSinger lock stitch ysewing machine ofcommerce as exemplified U. S. PatentNo.'"'1,105,968 to which attention is v directed fonamore v'complete"disclosure of theV drivinginecha'nism; n c, Y

According tomy invention, the usual rotaryV iliookorloop takerlBislafliXed to the forward'end tensioning means. for` tl1e-'low'erV sewing machine embodying 1 l "cylindrical casingzl having open front and rear r of a tubular operating shaft v| 6V therefor journaled in front and rear bearing sleeves II, I'I'r mounted Vin front and rear bearings I8, I8 depending from the bed plate I. The,tubular operating shaft I6 extends beneath and slightly, beyond the before-mentioned bevel gear I4 into a housingV I9 suitably secured to the under side ofthe bed plate I and to the rear bearing |8. A bevel gear |6. fast onsaid tubular shaft Iii` meshes with the bevel gear 4' whereby said shaft |6 is driven as will be clear.l Theratio of drive between the V'rotary hook or looptaker I5 and the needle bary is one revolution of th-e former to one reciprocation'of thelatter.

Suitably mountedrin the rotary hook or loop taker` |5,V in substantially thesame relation there'- to asthe vusual bobbin casing of the above desig- V`nated machinegis a ycombined guide and tensioning device 20 forl thelower thread comprising a sides with the Aexception of a. transverse central bar 22 extending across its rear side thereof.

The casing 2| is located directly beneath the needle I I and has a needle clearance opening 23, 'therein fora purpose presently seen. Secured to the cross-barr22 and within the casing 2| is a thread guiding nipple 24 of tapered form having its rear end` aligned with the tubular shaft I6. `The nipple 24 inclines upwardly and rearwardly and terminates adjacent toy a resilient thread j tensioning member 2 5 clamped to the front edge 26 of the casing 2| by a screw 21. The casing 2| is removablyr secured in the rotaryhook or loop taker 4I 5f by suitable means. (not shown) f and slightly spacedfrom the latter to provide a slight c clearance therebetween so that the rotary hook or loop taker `I is freely rotatable around said casing 2|. A latch member, 28 mounted` on a fixed part ofthe machine cooperateswith a notch 29` 'in the front edge 26 of the casing 2| to hold the combined guide and `tensioning ldevice k20A stationary.l The front edge 26 of the casing 2| inclines downwardly and rearwardly so that the' loop taker` 5fwill extend forwardly beyond said edge 26 of the casing 2| at Ythe bottom of the latter for a. purpose presently seen. Y suitablyv mounted upon arxed support 30 at 1 the balancel Wheel end of the machine is a pair of thread spindles 3| and 32 for the lower and 'n upper threads, respectively, and rotatably mounted, in any suitable mannerfonjsaid support 30. A pair of thread guides 33 extend upwardly from l. saidsupport in Yoverlyingrelation to the spin- `dles 3| and 32.' A tubular arcuate thread guide 34 is suitably secured at'one end to the support 36 to extend to an opening 35 in the rear wall of the housing I8 in axially alignment with the tubular drive shaft I6. Intermediate the spindles 3| and 32 and mounted on the support 30 is a pair of thread tensioning disks 36. Thetensioning disks v36 are relatively adjustable to impose a variable tension upon the thread and by means of a knurled thumb nut 31 and a tension spring 38.

The'upper thread 39 is led from the spindle 32 through one of the thread guides 33, to rsuitable thread guides 40 on the arm 3 and thenY in the usual manner around the tensioning disks l,

through the thread take-,up lever 6 and the thread .f

The lower loop 42 kis` carried by the loop taker I5 at which guides 8 and 9 to the needle I|. thread 4| is led from the spindle 3l over and between the tensioning disks 36, throughVVV the tubular thread guide 34, opening 35, tubular-shaft* I6, and nipple 24. From the-nipple 24`saidlower thread 4I is led beneathV the thread tensioning' KV42 is ypicked up'by thetusual hook Aor beak I5' of the loop taker I5, in the usualmanner, and carried part Yway around the thread guide and ten-v y 65 suitably Journaled in the bedr plate I and arm sioning device 2 I. Asbest shown in Figure the loop 42 is taken aroundthefront edgel oi' thev combined thread guide and tensioning devicerZIl,

that is to say, in front of the latter, and over the lower thread 4|, until the hook I5Yis inA its lowermost position and said loop substantially vertical. At this point the loop 42 is picked off `the hook I5 and carried up to a position subjacent the needle Il so that upon lth'evnext down stroke of the needle thelatterwill enter theloop to form a chain stitch. Thisv operation is effected by pick up mechanism nowto be described. y f

The basic element of the loop pick up mechanism (Figures 1 and 4) is an eccentric link Vmotion 43 contained, for the greater part,'in a housing 44`located beneath the throat plate I2 in ad- Vance of the combined thread guide and tensioning device 26. Said motion 43 comprises an eccentric 45 fast on a shaft 46 journaled, atV a right angle to the shaft I6, in bearings, as at 4l, extending from the front wall of the housing 44, an eccentric strap 48, and a rod 49 integral with said strap and extending therefrom toward said ten# sioning devicev 20. n extends through a guide slot 5|!l in 'aA guide bar 5I, in said housing 44, whereby when thehshaft 46 is rotated the rod 49 is reciprocated toward and from said tensioning device 20 and at the Sametime oscillated vertically. Pivoted, as at 52, on the free endy ofY the rod 49A for vertical swinging movement thereonv and to be reciprocated thereby is a pick up link, or bar, 53 extending toward the tensioning device 20 and termit* nating at its free endvin ay down turned snatch hook 54, pivoted thereon, as Vat 55, for lateral swinging movement and tensioned against ysiuch 53 is guided in its movement jby. a pair of vertically slotted guide bars r59,'a`n'df6'6l upstandling from ,the'bottom ofthe housing 44. Asuitable Prine @I Secured .in .the Shire-L'. .Qf @er 'Per il? .The free `end of the` rod 49V l this purpose. y t vloop'42'by thenlink 53 and snatch hook 54 they loop is continuously shortenedV bythe usual tenand loosely bearing against the link V53 tensions the latter against upward movement. Cooperating with the pick up link 53 is a cam 62 rotatably mounted on the guide bar 60 subjacent said link and adapted during each revolution to cam said link upwardly, against the tension of thev spring 6|, on the pivot 52 so that the snatch hook 54 is located above thelevel of the top of the loop taker I5 as shown in dotted lines in Figure l. Cooperating with the snatch hook 54 to cam the same laterally isa cam lug 63 upstandingirom the bottom 'of' the casing 2| on the inner face thereof and for a purposepresently seen.

nfthe before described position to which the point in the machine operation the needle II is nearing the limit-ofV its npstrokeposition, the

position of the described parts of the loop pick up mechanism'isas follows. The pick up link y53 is in the limit of its down stroke position and slightly in advance of the cam 62 and loop taker hookl5. The eccentric 45 is positioned to impart a slight forward thrust to said link 5! upon `initial rotation thereof, and the cam 62 is in position to elevate said link 53 following upon said forward thrust. 'Ihis position of the parts is clearly illustrated in Figures 1, 3 and 4. The eccentric 45 andcarn 62 are driven by the following drive mechanism; suitably journaled in the bearings 8, I8 to extend at its front and rear ends into the housings 44 and I9 isa driven shaft 64. rhe shaft 64 is driven by means of a jack shaft 3 along side the jack shaft I3 with one end geared to the drive shaft I3 by beveled gearing 66 and its other end similarly connected to the shaft 64 by gearingil. The other end of the shaft 64 is operatively connected to the shaft 46 by beveled gearing 6.8 and to the cam 62 by a pair of gear pinions 69 and l0 ,fast on the shaft 64 and cam 62 respectively. The described drive to the shaft 46 isso arranged and timedthat during approximately the last half revolution of the f loop taker I5 the eccentric 45 makes a complete revolution and theL cam 62 a half revolution.

beak I5* and the loop 42 snatched off said beak 'I5'. VlThe link'53 and snatch hook 54 are new retracted during which operation the cam Y62 raises said link upwardly to the before described elevated position thereof,` the eccentric describing substantially 'a Vhalf revolution. The eccentric now executes substantially another half revolution and thrusts the snatchhook 54 with the loop V42 thereon belowV the needle H it VVbeing understood that said needle is sufliciently elevated for During this *manipulation of the .by said hook cammed laterally ahead of the sioning operation exerted by the thread take vup lever V. Substantially coincidentally with-location of the loop Y42 beneath the needlelrl the Vlating the snatch hook 54 and the eccentric 62 releases the link 53. At the end of the second revolution of said eccentric, which occurs during substantially the i'lrst half cycle of revolution of the` loop taker I5 and formation and positioning of another loop 42 in the manner previously described, the link 53 and snatch hook 54 have been retracted and advanced a'nd lowered by the spring 6| to the starting position previously indicated.

In the positioning` of the loop 42 beneath the needle l the usual chain stitch is formed as will be obvious. However, as an incident to such positioning of the loop 42 each loop is wrapped around the lower thread 4|, or vice versa, so that on one side of the material stitched the lower thread is wound around the loops of the chain as shown in Figure 5. Because of the tension effected through the medium of the tensioning member 25 the chain is pulled tighter .by the lower thread 4| than in the usual machines and reinforced on one side of the material by said lower thread. The lower thread 4| may be distinctively colored for ornamental purposes or for identifying the one side of the fabric. y

The lower thread 4| may be inserted through the tubular thread guide 34, tubular shaft I6 and nipple 24 by means o-f a threading hook 12 of flexible metal inserted through the parts mentioned in a manner which will be understood.

The foregoing will, it is believed, suiiice to impart a clear understanding of the invention but it is to be understood that the present disclosure is illustrative rather than restrictive and that changes in form and relation of parts described may be resorted to fallingwithin the scope of the protection prayed.

What I claim is:

1. In a sewing machine, the combination with a reciprocatory needle and a source of Athread supply for said needle, of a rotary loop taker below said needle operative to engage the thread and form a loop therein, and loop pick up mechanism operative to free the loop from engagement with said loop taker and to carry said loop into a position intermediate said needle and loop taker. K

2. In a sewing machine, the combinationwith a reciprocatory needle and a source of thread supply for said needle, of a rotary loop taker below said needle operative to engage the thread and form a loop therein, and loop pick up mechanism operative to free the loop from engagement with said loop taker and to carry said loop into a position intermediate said needle and loop taker and including ahook member mounted for vertical swinging and reciprocatory movement, and means for moving said hook member.

3. In a sewing machine, the combination with a reciprocatory needle, and a source of thread supply for said needle, of a rotary loop taker below said needle operative to engage the thread and form a loop therein, and loop pick up mechanismoperative to free the loop from engagement with said loop taker and to carry said loop into a position intermediate said needleand loop taker, and including a pick up bar mounted for vertical swinging and reciprocatory movement, a snatch hook on said bar swingable thereon, means for moving said bar, and means to swing said hook comprising a stationary cam engaged by said hook as an incident to movement of said bar in onedirection.

4. In a sewing machine, the combination with a reciprocatory needle of a rotary loop taker mounted below said needle and having an axial opening therein, a combined thread guide and tensioning device comprising a cylindrical casing stationarily mounted adjacent to said loop taker axially of the latter, a tubular thread guide in said casing axially aligned at one end with the opening in said loop taker, a thread tensioning i.

member on the outside of said casing to which the thread extends from said guide, a thread supply from' which the thread extends through said opening and thread guide, kand means for rotating said loop taker.

5. In a sewing machine, the combination with a reciprocatory needle, of loop forming mechanism comprising a tubular shaft rotatably mounted below said needle, a rotary'loop taker iixed on one end of said shaft adjacent said needle, a combined thread guide and tensioning device including a cylindrical casing stationarily mount- .ed adjacent to said loop taker axially of the latter, a thread guiding nipple fixed in'said casing with one end thereof disposed axially of said casing, a thread tensioning member on the outer face of said casing to which the thread extends from said nipple, a thread supply from which the thread extends through said shaft, looper and nipple, and means for rotating said shaft.

6. In a sewing machine, the combination with a reciprocatory needle, of loop forming mechanism comprising a tubular shaft rotatably mounted below said needle, a rotary loop taker xed on one end of said shaft adjacent said needle, a combined thread guide and tensioning device including a cylindrical casing stationarily mounted adjacent to said loop taker axially of the latter, a thread guiding nipple iixed in said casing with one end thereof disposed axially of said casing, a thread tensioning member on the outer face of said casing to which the thread extends from said nipple, a drive for said shaft including gearing, a housing for said gearing into which said shaft extends, a tubular thread guide extending into said housing into axial alignment with said shaft, and a thread supply from which the thread is led to said tubular guide, shaft, and loop taker into said nipple.

BOOKER W. DAVIDSON. 

